Microplastic (MP) pollutants of 100 nm to 5 mm diameter are rapidly emerging as a consequence of our ubiquitous dependence on plastics. MPs are now routinely found in sea and fresh water, food and beverages, as well as intestinal tracts of fish and mammals. Public awareness of the problem is growing with an increasing frequency of reports in academic journals and popular media, but the development of standards and acceptable pollutant limits has been hampered for several reasons. Most notably, lack of affordable and standardized isolation protocols have made it impractical to conduct widespread surveillance of environmental MP levels, thus determining the health consequences of MP exposure has been limited. Consequently, regulatory and standards bodies (EPA, NSF/ANSI) are hesitant to define MP contamination limits. We believe this dilemma can be broken with new easy-to-use MP isolation products. Building on its 10+ year track-record of marketing lab products, SiMPore will develop new MP isolation products (the SEA-PUR? MP isolation kit) that are based on its world-leading silicon nanomembranes. These products will rely upon the high permeability, optical transparency, and plastic-free background properties of silicon microslit nanomembranes to enable the easy isolation and chemical identification of environmental MPs. During this 9-month SBIR project, we will develop a minimum viable product that will enable researchers to isolate MPs by size and determine particle concentration by imaging filtercaptured MPs retained on the membranes. Using lab-prepared and environmental samples, we will optimize a usage protocol involving peroxidation+base digestion, followed by Nyle red staining of surviving MPs, for easy fluorescent imaging and MP counting. We will demonstrate that silicon microslit nanomembranes enable plastic-free spectroscopic chemical fingerprinting of MPs, using a range of Raman and FTIR microscopy systems and a variety of MP types. We will further demonstrate utility by sending product prototypes to: 1) Dr. Belinda Sturm (U Kansas) for MP testing using samples from a nationwide collection of effluent from waste water treatment plants; and 2) MP testing in water samples collected throughout western NY by local high school students participating in the U. Rochester?s Life Science Learning Center?s programs. Subcontractors at U. Rochester will also use isolated MP environmental samples and develop a protocol for transferring these MPs into proof-of-concept toxicological studies using an in vitro model of intestinal absorption (Caco-2 barrier models).